Malignant brain tumors are a significant health problem in children and adults and are largely unmanageable. As a metabolic disorder involving the dysregulation of glycolysis and respiration (the Warburg effect), malignant brain cancer can be managed through changes in metabolic environment. In contrast to malignant brain tumors that are mostly dependent on glycolysis for energy, normal neurons and glia readily transition to ketone bodies (β-hydroxybutyrate) for energy in vivo when glucose levels are reduced. The transition from glucose to ketone bodies as a major energy source is an evolutionary conserved adaptation to food deprivation that permits the survival of normal cells during extreme shifts in nutritional environment. Only those cells with a flexible genome, honed through millions of years of environmental forcing and variability selection, can transition from one energy state to another. We propose a different approach to brain cancer management that exploits the metabolic flexibility of normal cells at the expense of the genetically defective and less metabolically flexible tumor cells. This approach to brain cancer management is supported from recent studies in orthotopic mouse brain tumor models and in human pediatric astrocytoma treated with calorie restriction and the ketogenic diet. Issues of implementation and use protocols are discussed.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Cancer cells (vs. normal cells) demonstrate evidence of oxidative stress, increased glycolysis, and increased pentose cycle activity. The oxidative stress in cancer cells has been hypothesized to arise from mitochondrial dysfunction leading to increased levels of hydroperoxides, and cancer cells have been proposed to compensate for this defect by increasing glucose metabolism. Glucose metabolism has also been shown to play a role in hydroperoxide detoxification via the formation of pyruvate (from glycolysis) and NADPH (from the pentose cycle). Furthermore, in cancer cells, glucose deprivation as well as treatment with 2-deoxyglucose (2 DG) has been shown to induce oxidative stress and cytotoxicity. Additionally, transformed cells have been shown to be more susceptible to glucose deprivation (and 2DG-)-induced cytotoxicity and oxidative stress than untransformed cells. These results support the hypothesis that cancer cells have a defect in mitochondrial respiration leading to increased steady state levels of O _{2^• - and H 2 O2} , and glucose metabolism is increased to compensate for this defect. The application of these findings to developing cancer therapies using 2DG combined with inhibitors of hydroperoxide metabolism to induce radio/chemosensitization is discussed, as well as the possibility that FDG-PET imaging may predict tumor responses to these therapies.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Higher rates of glucose usage generally correlate with poor prognosis in several types of malignant tumours. Experimental studies (both in vitro and in vivo) have shown that 2-deoxy-D-glucose (2-DG), a glucose analog and glycolytic inhibitor, enhances radiation-induced damage selectively in tumor cells while protecting normal cells, thereby suggesting that 2-DG can be used as a differential radiomodifier to improve the efficacy of radiotherapy. Clinical trials undertaken to study the feasibility, safety, and validity of this suggested approach will be described. Based on 2-DG-induced radiosensitization observed in primary organ cultures of cerebral glioma tissues, clinical trials were designed taking into consideration the radiobiology of gliomas and pharmacokinetics of 2-DG. Phase I/II clinical trials have unequivocally demonstrated that a combination of 2-DG (200-300 mg 2-DG per kg body weight orally administered after overnight fasting, 20min before irradiation) with large weekly fractions (5 Gy/fraction) of low-LET radiotherapy is well tolerated without any acute toxicity or late radiation damage to the normal brain tissue. Nonserious transient side effects similar to hypoglycemia induced disturbances like restlessness, nausea, and vomiting were observed at the 2-DG doses used. Data from these trials involving more than 100 patients have clearly indicated a moderate increase in the survival, with a significant improvement in the quality of life with clinicopathological evidence of protection of normal brain tissue. A phase III multicentric trial to evaluate the efficacy of the combined treatment is in progress. Directions for future studies are discussed.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

The glucose analog 2-deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolytic ATP production, is the most widely investigated metabolic inhibitor for targeting glucose metabolism. Besides depleting energy in cells, 2-DG has also been found to alter N-linked glycosylation leading to unfolded protein responses and induce changes in gene expression and phosphorylation status of proteins involved in signaling, cell cycle control, DNA repair, calcium influx, and apoptosis. Inhibition of cell proliferation and induction of apoptosis have been observed as cytotoxic effects in a wide variety of tumor cells in vitro, while sensitization of tumor cells to ionizing radiation and certain chemotherapeutic drugs is associated with enhanced mitotic as well as apoptotic cell death induced by the primary therapeutic agent. Therefore, there has been a considerable amount of interest in developing 2-DG as a therapeutic agent or adjuvant in the radiotherapy and chemotherapy of tumors.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Background: Accelerated glucose uptake for anerobic glycolysis is one of the major metabolic changes found in malignant cells. This property has been exploited for imaging malignancies and as a possible anticancer therapy. The nonmetabolizable glucose analog 2-deoxyglucose (2 DG) interferes with glucose metabolism leading to breast cancer cell death. Aims: To determine whether 2DG can synergize with chemotherapeutic agents commonly used in breast cancer treatment and identify cellular characteristics associated with sensitivity to 2DG. Materials and Methods: SkBr3 breast cancer cells were incubated with varying concentrations of 5-fluorouracil (5FU), doxorubicin, cisplatin, cyclophosphamide, or herceptin with or without 2DG. Cell viability was measured using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results: Combining 2DG with doxorubicin, 5 FU, cyclophosphamide, and herceptin resulted in enhanced cell death compared with each agent alone, while in combination with cisplatin, the amount of cell death was additive. Mouse embryo fibroblasts (MEF) mutated for p53 (-/-) were 30% more sensitive to the cytotoxic effects of 2DG than the parental cell lines. Cells mutated for Bax/Bac, genes involved in protection from apoptosis, are slightly more sensitive than the parental cell lines. Conclusions: These results indicate that 2DG acts synergistically with specific chemotherapeutic agents in causing cell death and the class of chemicals most sensitive appear to be those which cause DNA damage.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Background: The specific signaling that occurs between the endoplasmic reticulum (ER) and the nucleus in response to ER stress is known as the unfolded protein response (UPR). Specific induction of GRP78 (glucose-regulated protein of Mr 78 kDa) is an integral component of ER stress and the UPR. We first discovered that the up-regulation of GRP78 is associated with augmented sensitivity/apoptosis of cancer cells to clinically used alkylating/platinating agents. Objectives: To decipher molecular mechanisms that associate induction of the UPR/GRP78 with augmented sensitivity/apoptosis to cisplatin. Materials and Methods: A549 cells were exposed to 2-deoxyglucose (2dG) to induce the UPR/GRP78, followed by cisplatin treatment. We used human cDNA microarray containing 42,000 ESTs as well as pathway-specific macroarrays for apoptosis, cell cycle, and MAP kinase signaling pathways containing 100-280 genes and subsequently examined the pertinent transcript levels. The results obtained from these studies were confirmed by examining relevant protein levels and the enzymatic activity. Results: We demonstrate that the induction of UPR/GRP78 alone causes a decrease in the transcript levels of DNA repair genes and DNA damage check point genes, and an increase in the transcript levels of apoptotic genes. Furthermore, we show that cisplatin treatment after the induction of UPR/GRP78 is facilitating the mitochondria-mediated apoptotic cascades through the initial activation of caspase-2 and down-regulation of genes involved in DNA repair. Conclusions: Our study will shed new insight as to the increased understanding of the mechanisms of the UPR/GRP78 modulation of molecular and cellular responses to cisplatin that will allow strategies for transferring bench side results to the bed.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Radioimmunotherapy (RIT) has been proven effective in the treatment of radiosensitive non-Hodgkin lymphoma but, for radioresistant solid tumors, new approaches are necessary to improve the clinical effectiveness. A real improvement has been the introduction of the pretargeting technology which appeared to be able to significantly increase tumor-to-normal organ uptake ratios.Another very promising approach consists in associating RIT with other treatment modalities. Finally the use of alpha particle-emitting radionuclides such as astatin-211 or bismuth-213 (alpha-RIT) should allow to efficiently eradicate disseminated microscopic clusters of tumor cells or isolated tumor cells which fit well with the short path length of alpha particles.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Background: 2-Deoxy-D-glucose (2-DG), a glycolytic inhibitor, was observed earlier to increase DNA, chromosomal, and cellular damage in tumor cells, by inhibiting energy-dependent repair processes. Lonidamine (LND) selectively inhibits glycolysis in cancer cells. It damages the condensed mitochondria in these cells, impairing thereby the activity of hexokinase (predominantly attached to the outer mitochondrial membranes). It inhibits repair of radiation-induced potentially lethal cellular damage in HeLa and Chinese hamster (HA-1) cells. However, other than a preliminary study on human glioma (BMG-1) cells in this laboratory, the effects of LND on radiation-induced cytogenetic damage have not been reported earlier. Aims: These studies were carried out to investigate the effects of LND and 2-DG on cell proliferation, viability, and radiation response in the same human glioma cell line, under identical conditions. The respective drug concentrations were selected on the basis of earlier studies. Materials and Methods: Human glioma (U373MG) cells were grown in the presence of LND or 2-DG for 2 days. Proliferation response and viability of U373MG human glioma cells were studied by cell counts and uptake of trypan blue dye. Radiosensitization (increase in micronuclei formation) was studied after short-term (4 h postirradiation) drug treatments. Observations: Both the drugs (1) inhibited proliferation response in a concentration-dependent manner; (2) did not induce micronuclei formation in the unirradiated cells; and (3) significantly increased radiation-induced micronuclei formation at nontoxic concentrations. Conclusions: These data suggest that the short-term presence of either lonidamine or 2-DG-at clinically relevant and nontoxic concentrations-could increase the treatment response of malignant gliomas at optimum radiation doses, reducing thereby the side effects of radiotherapy.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

The glycolytic inhibitor 2-deoxy-D-glucose (2-DG) has been used as a therapeutic agent and as an adjuvant in cancer therapy with either weekly fractions of the treatment or daily administration. While the weekly fraction has often been found to be nontoxic and effective, other treatment regimes are tolerated to a relatively lesser extent. It was therefore, considered worthwhile to investigate the efficacy of short- and long-term exposure of tumor cells to 2-DG under the controlled conditions. Seven-day-old MTS were exposed to 2-DG (5 mM, equimolar to glucose concentration in media) for different time intervals (30 min to 24 h) trypsinized and plated for clonogenecity. Alternatively, spheroids were grown either continuously in the presence of 2-DG or were treated with 2-DG for 2 h (short-term exposure) and grown in 2-DG-free media for 21 days and assessed for spheroid growth, cell viability, apoptosis, cytogenetic damage, mitochondrial status, and oxidative stress. Exposure of spheroids to 2-DG for 2-4 h induced 30% cell death (SF 0.70) while, a 24-h exposure resulted in only a marginal decrease in clonogenecity (SF 0.95). Furthermore, the spheroids disintegrated completely by 28 days in the case of 2-h exposure to 2-DG, while spheroids grown continuously in the presence of 2-DG repopulated. The cytotoxicity following short-term exposure of MTS to 2-DG was primarily due to the induction of apoptosis revealed by morphological features as well as flow cytometric analysis of the DNA content. Interestingly however, cytogenetic damage (micronuclei induction) was observed in spheroids that were continuously exposed to 2-DG. Short-term exposure to 2-DG resulted in a significant increase in ROS levels and a reduction in the levels of unoxidized cardiolipin as measured by NAO suggesting the involvement of mitochondria leakiness leading to oxidative stress which, could be responsible for apoptotic cell death observed under these conditions. However, continuous exposure to 2-DG resulted in a moderate level of oxidative stress leading to the genomic instability. Preliminary studies also show that spheroids exposed continuously to 2-DG result in the development of resistance to certain chemotherapeutic drugs which could be correlated with elevated levels of mdr1. The present results suggest that a persistent down-regulation of glycolysis (as seen here with continuous exposure to 2-DG) could activate prosurvival responses besides inducing moderate levels of oxidative stress resulting in the development of resistance against therapeutic agents.

[ABSTRACT]  [FULL TEXT]  [PDF]  [PubMed]

Normal tissue toxicity is one of the major limiting factors in cancer therapy. Damage to normal tissues and critical organs restricts the use of higher therapeutic doses thereby compromising the efficacy. The glucose analog 2-deoxy-D-glucose (2-DG), an inhibitor of glycolytic ATP production has been shown to enhance radiation- and chemotherapeutic drug-induced damage in a number of cancer cells under in vitro and in vivo conditions while sparing or protecting normal cells. This review summarizes current understanding on the protection of normal cells and tissues against radiation- and chemotherapeutic drug-induced damage by 2-DG that makes this glucose analog an ideal adjuvant in cancer therapy.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

The development of an approach based on the energy-linked modification of DNA repair and cellular recovery processes using 2-deoxy-D-glucose (2-DG; inhibitor of glycolytic ATP production) has shown promising results in a number of model systems of cancer. Following encouraging results on the tolerance and toxicity (acute as well as late effects) of the combination (2-DG and hypofractionated radiotherapy) in Phase I and II clinical trials, its efficacy is currently under evaluation in Phase III clinical trials for glioma patients. Since heterogeneous physiologic and metabolic status in tumors as well as host-tumor interactions influence the local tumor control, which coupled with systemic disturbances could determine the cure (long-term tumor free survival), investigations on the in vivo responses of tumors to the combined treatment have received considerable attention. This communication provides a brief overview on the in vivo studies related to radio- and chemosensitization of tumors by 2-DG, besides the normal tissue toxicity induced by the combined treatment of 2-DG and radiation or chemotherapeutic drugs.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

Background: 2-Deoxy-D-glucose (2-DG), a structural analog of glucose is an effective inhibitor of glucose metabolism and ATP production. It selectively accumulates in cancer cells and interferes with glycolysis leading to cell death. 2-DG is shown to differentially enhance the radiation-induced damage in cancer cells both under euoxic and hypoxic conditions. A combination of 2-DG and ionizing radiation selectively destroys tumors while protecting the normal tissue. 2-DG is being advocated as an adjuvant in the radiotherapy and chemotherapy of cancer. Objective: The present investigation focuses on the modulatory effect of 2-DG on mitomycin C- (MMC) and 4-nitroquinoline-1-oxide (4-NQO)-induced cytogenetic damage in bone marrow cells of Swiss albino mice in vivo. Materials and Methods: Experimental animals were pretreated with 2-DG (500 mg/kg, i.p.) for five consecutive days followed by MMC (2 mg/kg, i.p) or 4-NQO (15 mg/kg, i.p.), 24h prior to sacrifice. Control animals were given either the mixture of olive oil and acetone (3:1) or distilled water. Bone marrow cells were processed for the micronucleus assay and metaphase analysis for estimating cytogenetic damage. Results: 2-DG significantly (P < 0.001) reduced the frequency of aberrant cells induced by MMC (~90%) and 4-NQO (~74%). Incidence of micronucleated polychromatic erythrocytes (MnPCEs) induced by the mutagens were reduced up to 68%. Conclusion: 2-DG effectively reduces the MMC-and 4-NQO-induced genotoxicity.

[ABSTRACT]  [FULL TEXT]  [PDF]  [PubMed]

2-deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolysis, enhances radiation damage selectively in tumor cells by modulating damage response pathways resulting in cell death in vitro and local tumor control. Phase I and II clinical trials in patients with malignant glioma have shown excellent tolerance to a combined treatment of orally administered 2-DG and hypofractionated radiotherapy without any acute toxicity and late radiation damage. Phase III efficacy trials are currently at an advanced stage. Re-exploratory surgery performed in 13 patients due to persistent symptoms of elevated ICP and mass effect at different follow-up periods revealed extensive tumor necrosis with well-preserved normal brain tissue adjoining the tumor included in the treatment volume as revealed by a histological examination. These observations are perhaps the first clinical evidences for differential effects of 2-DG on tumors and normal tissues in conformity with earlier in vitro and in vivo studies in normal and tumor-bearing mice.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]

[FULL TEXT]  [PDF]  [PubMed]

Background: Chemotherapy is the treatment of cancer with drugs, often used as either adjuvant or neoadjuvant or in conjunction with radiation and surgery. Unfortunately, majority of the drugs are toxic to normal tissues, the toxicity being resulting from multidrug protocol used to induce remissions and achieve tumor care. While it has been demonstrated for compounds like the 2-deoxy-glucose (2-DG) used as a modulator for radiation-induced damages, such studies were rarely reported for chemotherapeutic drugs. Objective: To study the effect of 2-DG on radiation-and chemotherapeutic drug-induced chromosomal aberrations in normal and tumor cells exposed in vitro. Materials and Methods: The peripheral blood lymphocytes (PBLs) and BMG-1 cells were exposed to radiation and chemotherapeutic drugs (bleomycin and mitomycin-C) in the presence and absence of 2-DG. The treated cells were cultured for various durations, arrested at either metaphase or cytokinesis stage of the cell cycle. The stable and unstable aberrations were recorded using Giemsa staining and FISH technique. The cell cycle kinetics was studied using fluorescence plus Giemsa (FPG) staining. Results: The presence of 2-DG reduced stable and unstable chromosome aberrations (CA) significantly (P < 0.001), in PBLs induced by radiation, bleomycin and mitomycin-C, when compared to cells treated with radiation or the drugs and increased significantly in BMG cells (P < 0.001). Furthermore, the presence of 2-DG altered the cell cycle kinetics in the PBLs and BMG-1 cells. Thus the overall results showed protection effect on the normal cell damages induced by radiation and chemotherapeutic drugs, while sensitizes the tumor cell. Conclusion: The obtained results suggest that 2-DG in combination with radiotherapy/chemotherapy could lead to an improvement in tumor therapy by sensitizing the tumor cells while protecting the normal cells.

[ABSTRACT]  [FULL TEXT]  [PDF] [CITATIONS]  [PubMed]